The invention relates to a flow regulator for gaseous or liquid media, comprising a housing, a regulating unit which changes its free-flow area, depending on the flow of the medium, and further comprising a distributor unit. The regulating unit may, for example, be a component which partly limits the flow area, which is mounted for spring-like movement in an axial direction, and which reduces the flow area as the pressure increases, by axial displacement in a tapered part of the housing.
In the simplest case the distributor means is a disc containing a plurality of small, evenly distributed holes, from which the medium emerges suitably divided into individual fine jets. For the sake of simplicity only water will be considered as the flowing medium here; however, the invention is not restricted to water, and corresponding statements may readily be applied to other flowing media, particularly gaseous substances.
Flow regulators of this type are often used on water taps to reduce water consumption or to keep it at a low level. In a flow regulator for water taps the distributor means mostly comprises a perforated disc of the type described above, and a group of coarse and fine screens spaced therefrom in the direction of flow. Apertures are provided in the wall of the housing surrounding the whole arrangement, between the distributor disc and the screens, and air is drawn through the apertures and mixed in with the water flowing through the regulator. The water then emerges from the screen arrangement suitably finely divided and mixed with air. Arrangements of this type with a distributor means, air suction apertures and a screen arrangement are also described as "aerating taps". However, most aerating taps do not have a regulating device.
So-called water-saving regulators or water-saving inserts are also known. Substantially the only difference between them and the aerating taps is that they have an additional flow limiter, which may be identical with the distributor disc, so that the whole free flow area, independently of pressure, is always smaller than in conventional taps with a bubbling effect. The flow volume is therefore reduced by substantially the same percentage as compared with conventional taps over the whole pressure range. These "water-saving regulators" do not generally have a regulating element as understood in the invention, where the flow area changes depending on the flow pressure, that is to say, becomes smaller as the flow pressure rises. The last-mentioned flow regulators are an attempt to obtain the most constant possible flow volume independently of the flow pressure.
Efforts are often made to set the volume flow rate through the regulator as far as possible at a very low pressure, and to hold the flow rate constant over the largest possible pressure range as the pressure rises. Efforts are also generally made to keep the whole construction of the regulator as simple as possible, so that it is easy and cost-effective to produce.
A flow regulator with the above-mentioned features is already known, in which the regulating means has a very simple structure. It comprises a substantially conical, flexible plastics element, in which slots extend radially from near the center, outwardly to the edge of the once but end before the outer edge of the regulating element. The slots may start from a central flow aperture in the cone. A regulating means of this type is mounted in the flow regulator with the conically converging end in the opposite direction to the flow, so that the individual segments into which the cone is divided by the slots are pushed axially and radially inwards by the pressure exerted on them. The slots between the segment are closed and the diameter of any central aperture provided becomes smaller, until all the segments lie firmly against each other and the cross section eventually does not change any more even if the pressure continues to rise.
With a simple regulating arrangement of this type it has already been found possible to keep the flow volume substantially constant over a pressure range from about 1 to 10 bar i flow regulators for water.
However, it is very difficult to stipulate the exact flow volume precisely owing to the manufacturing tolerances for the various components. In practice there are variations in the maximum volume flowing through within the regulating range (which may e.g. be from 1 to 10 bar) which have variations in the region of 10% and even more, in regulating means of substantially identical construction.
Nor does the curve for the flow volume per unit of time, plotted against the flow pressure, show an exactly constant value; it usually passes through a more or less pronounced maximum in the 2 to 3 bar flow pressure region.
At this state of the art the problem underlying the invention is to provide a flow regulator with the above-mentioned features, which is still relatively simple in construction yet enables more constant volume limitation to be maintained and is less sensitive to manufacturing tolerances of the individual components.